1. Field of the Invention
The present invention relates to a method and an apparatus for transmitting and receiving information for random access in a wireless communication system.
2. Description of the Related Art
In wireless communication, various methods of improving the demands of data communication and supporting a high-capacity data service have recently been suggested. In order to provide a high-capacity data service in view of increased demand for data communication, a high data rate is necessary, and the use of a high carrier frequency band is needed for the high data rate. However, as the carrier frequency is higher, a transmission distance of a signal is relatively shorter, thereby generating a problem of a decrease in service coverage.
In order to address these issues, technology for providing a high-capacity wireless communication service in order to increase a transmission distance of a signal and reduce interference between a neighbor cell has been developed. Beam forming is one technology for providing a high-capacity wireless communication service.
Beam forming refers to concentrating a transmission direction of a signal to a specific direction by using one or more array antennas or horn antennas by a transmission device. With beam forming, a transmission distance of a signal is increased and a signal transmitted in a direction other than a corresponding direction is decreased, so that unnecessary signal interference is effectively reduced.
A reception device may also use a reception beam forming using a reception antenna. In reception beam forming, a direction of signal reception is concentrated to a specific direction, so that a strength of a signal received in a corresponding direction is increased, and a signal received in a direction other than the corresponding direction is removed from a reception signal, so that an unnecessary interference signal may be blocked.
As described above, beam forming expands service coverage and reduces the quantity of interference, but needs to determine a direction and a form of a beam of each of a transmission device and a reception device in order to use an optimum channel.
For example, when the transmission device is a base station and the reception device is a mobile terminal, in a process of first starting communication, such as an initial random access, by the base station and the mobile terminal, a direction of a transmission beam of the mobile terminal does not correspond to a direction of a reception beam of the base station in a case of an uplink. Accordingly, it is necessary to perform a beam alignment process between the base station and the mobile terminal before the performance of the initial random access. The beam alignment process denotes a process of aligning the direction of the transmission beam of the mobile terminal with the direction of the reception beam of the base station. The base station and the mobile terminal determine the beams forming an optimum channel by performing the beam alignment process.